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# IO::Select.pm
#
# Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights reserved.
# This program is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.
package IO::Select;
use strict;
use warnings::register;
use vars qw($VERSION @ISA);
require Exporter;
$VERSION = "1.22";
@ISA = qw(Exporter); # This is only so we can do version checking
sub VEC_BITS () {0}
sub FD_COUNT () {1}
sub FIRST_FD () {2}
sub new
{
my $self = shift;
my $type = ref($self) || $self;
my $vec = bless [undef,0], $type;
$vec->add(@_)
if @_;
$vec;
}
sub add
{
shift->_update('add', @_);
}
sub remove
{
shift->_update('remove', @_);
}
sub exists
{
my $vec = shift;
my $fno = $vec->_fileno(shift);
return undef unless defined $fno;
$vec->[$fno + FIRST_FD];
}
sub _fileno
{
my($self, $f) = @_;
return unless defined $f;
$f = $f->[0] if ref($f) eq 'ARRAY';
($f =~ /^\d+$/) ? $f : fileno($f);
}
sub _update
{
my $vec = shift;
my $add = shift eq 'add';
my $bits = $vec->[VEC_BITS];
$bits = '' unless defined $bits;
my $count = 0;
my $f;
foreach $f (@_)
{
my $fn = $vec->_fileno($f);
if ($add) {
next unless defined $fn;
my $i = $fn + FIRST_FD;
if (defined $vec->[$i]) {
$vec->[$i] = $f; # if array rest might be different, so we update
next;
}
$vec->[FD_COUNT]++;
vec($bits, $fn, 1) = 1;
$vec->[$i] = $f;
} else { # remove
if ( ! defined $fn ) { # remove if fileno undef'd
$fn = 0;
for my $fe (@{$vec}[FIRST_FD .. $#$vec]) {
if (defined($fe) && $fe == $f) {
$vec->[FD_COUNT]--;
$fe = undef;
vec($bits, $fn, 1) = 0;
last;
}
++$fn;
}
}
else {
my $i = $fn + FIRST_FD;
next unless defined $vec->[$i];
$vec->[FD_COUNT]--;
vec($bits, $fn, 1) = 0;
$vec->[$i] = undef;
}
}
$count++;
}
$vec->[VEC_BITS] = $vec->[FD_COUNT] ? $bits : undef;
$count;
}
sub can_read
{
my $vec = shift;
my $timeout = shift;
my $r = $vec->[VEC_BITS];
defined($r) && (select($r,undef,undef,$timeout) > 0)
? handles($vec, $r)
: ();
}
sub can_write
{
my $vec = shift;
my $timeout = shift;
my $w = $vec->[VEC_BITS];
defined($w) && (select(undef,$w,undef,$timeout) > 0)
? handles($vec, $w)
: ();
}
sub has_exception
{
my $vec = shift;
my $timeout = shift;
my $e = $vec->[VEC_BITS];
defined($e) && (select(undef,undef,$e,$timeout) > 0)
? handles($vec, $e)
: ();
}
sub has_error
{
warnings::warn("Call to deprecated method 'has_error', use 'has_exception'")
if warnings::enabled();
goto &has_exception;
}
sub count
{
my $vec = shift;
$vec->[FD_COUNT];
}
sub bits
{
my $vec = shift;
$vec->[VEC_BITS];
}
sub as_string # for debugging
{
my $vec = shift;
my $str = ref($vec) . ": ";
my $bits = $vec->bits;
my $count = $vec->count;
$str .= defined($bits) ? unpack("b*", $bits) : "undef";
$str .= " $count";
my @handles = @$vec;
splice(@handles, 0, FIRST_FD);
for (@handles) {
$str .= " " . (defined($_) ? "$_" : "-");
}
$str;
}
sub _max
{
my($a,$b,$c) = @_;
$a > $b
? $a > $c
? $a
: $c
: $b > $c
? $b
: $c;
}
sub select
{
shift
if defined $_[0] && !ref($_[0]);
my($r,$w,$e,$t) = @_;
my @result = ();
my $rb = defined $r ? $r->[VEC_BITS] : undef;
my $wb = defined $w ? $w->[VEC_BITS] : undef;
my $eb = defined $e ? $e->[VEC_BITS] : undef;
if(select($rb,$wb,$eb,$t) > 0)
{
my @r = ();
my @w = ();
my @e = ();
my $i = _max(defined $r ? scalar(@$r)-1 : 0,
defined $w ? scalar(@$w)-1 : 0,
defined $e ? scalar(@$e)-1 : 0);
for( ; $i >= FIRST_FD ; $i--)
{
my $j = $i - FIRST_FD;
push(@r, $r->[$i])
if defined $rb && defined $r->[$i] && vec($rb, $j, 1);
push(@w, $w->[$i])
if defined $wb && defined $w->[$i] && vec($wb, $j, 1);
push(@e, $e->[$i])
if defined $eb && defined $e->[$i] && vec($eb, $j, 1);
}
@result = (\@r, \@w, \@e);
}
@result;
}
sub handles
{
my $vec = shift;
my $bits = shift;
my @h = ();
my $i;
my $max = scalar(@$vec) - 1;
for ($i = FIRST_FD; $i <= $max; $i++)
{
next unless defined $vec->[$i];
push(@h, $vec->[$i])
if !defined($bits) || vec($bits, $i - FIRST_FD, 1);
}
@h;
}
1;
__END__
=head1 NAME
IO::Select - OO interface to the select system call
=head1 SYNOPSIS
use IO::Select;
$s = IO::Select->new();
$s->add(\*STDIN);
$s->add($some_handle);
@ready = $s->can_read($timeout);
@ready = IO::Select->new(@handles)->can_read(0);
=head1 DESCRIPTION
The C<IO::Select> package implements an object approach to the system C<select>
function call. It allows the user to see what IO handles, see L<IO::Handle>,
are ready for reading, writing or have an exception pending.
=head1 CONSTRUCTOR
=over 4
=item new ( [ HANDLES ] )
The constructor creates a new object and optionally initialises it with a set
of handles.
=back
=head1 METHODS
=over 4
=item add ( HANDLES )
Add the list of handles to the C<IO::Select> object. It is these values that
will be returned when an event occurs. C<IO::Select> keeps these values in a
cache which is indexed by the C<fileno> of the handle, so if more than one
handle with the same C<fileno> is specified then only the last one is cached.
Each handle can be an C<IO::Handle> object, an integer or an array
reference where the first element is an C<IO::Handle> or an integer.
=item remove ( HANDLES )
Remove all the given handles from the object. This method also works
by the C<fileno> of the handles. So the exact handles that were added
need not be passed, just handles that have an equivalent C<fileno>
=item exists ( HANDLE )
Returns a true value (actually the handle itself) if it is present.
Returns undef otherwise.
=item handles
Return an array of all registered handles.
=item can_read ( [ TIMEOUT ] )
Return an array of handles that are ready for reading. C<TIMEOUT> is
the maximum amount of time to wait before returning an empty list, in
seconds, possibly fractional. If C<TIMEOUT> is not given and any
handles are registered then the call will block.
=item can_write ( [ TIMEOUT ] )
Same as C<can_read> except check for handles that can be written to.
=item has_exception ( [ TIMEOUT ] )
Same as C<can_read> except check for handles that have an exception
condition, for example pending out-of-band data.
=item count ()
Returns the number of handles that the object will check for when
one of the C<can_> methods is called or the object is passed to
the C<select> static method.
=item bits()
Return the bit string suitable as argument to the core select() call.
=item select ( READ, WRITE, EXCEPTION [, TIMEOUT ] )
C<select> is a static method, that is you call it with the package name
like C<new>. C<READ>, C<WRITE> and C<EXCEPTION> are either C<undef> or
C<IO::Select> objects. C<TIMEOUT> is optional and has the same effect as
for the core select call.
The result will be an array of 3 elements, each a reference to an array
which will hold the handles that are ready for reading, writing and have
exceptions respectively. Upon error an empty list is returned.
=back
=head1 EXAMPLE
Here is a short example which shows how C<IO::Select> could be used
to write a server which communicates with several sockets while also
listening for more connections on a listen socket
use IO::Select;
use IO::Socket;
$lsn = IO::Socket::INET->new(Listen => 1, LocalPort => 8080);
$sel = IO::Select->new( $lsn );
while(@ready = $sel->can_read) {
foreach $fh (@ready) {
if($fh == $lsn) {
# Create a new socket
$new = $lsn->accept;
$sel->add($new);
}
else {
# Process socket
# Maybe we have finished with the socket
$sel->remove($fh);
$fh->close;
}
}
}
=head1 AUTHOR
Graham Barr. Currently maintained by the Perl Porters. Please report all
bugs to <perlbug@perl.org>.
=head1 COPYRIGHT
Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights reserved.
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
=cut
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